clang-format: Fix incorrect &&-detection in macros.

Before:
  #define A(a, b) (a &&b)

After:
  #define A(a, b) (a && b)

This fixes llvm.org/PR19343.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@206165 91177308-0d34-0410-b5e6-96231b3b80d8